Cost of Aseptic Revision Total Knee Arthroplasty at a Tertiary Medical Center

BackgroundRevision total knee arthroplasty (TKA) involves varying levels of case complexity and costs depending on the following: (1) number of components revised, (2) duration of operating room time, and (3) length of hospital stay. However, the cost associated with different types of aseptic TKA revisions, based on number and type of components revised, is not well described. We sought to determine differences in cost associated with different revision types, and to correlate this with average national hospital and surgeon reimbursement based on current Centers for Medicare and Medicaid Services data.MethodsThis is a retrospective review of aseptic revision TKAs performed at a single tertiary referral center from 2015 to 2018. Patient demographic data, operating room time, and direct surgery and total hospital costs obtained from an internal accounting database (Enterprise Performance Systems, Inc) were collected. Patients were stratified by the components revised (polyethylene liner only, tibia only, femur only, or both femur and tibia). We hypothesized that direct surgery and total hospital costs would increase as case complexity increased from poly exchange to single-component revisions and both-component revisions.ResultsIn total, 106 patients were included (19 poly exchanges, 10 tibia-only revisions, 13 femur-only revisions, and 64 both-component revisions). Operating room time was significantly lower for poly exchange than all other groups (P < .001). Direct surgery and total hospital costs were significantly lower for poly exchange than all other groups (P < .001), and were significantly lower for tibia-only and femur-only revisions compared to both-component revisions (P < .001). Average national surgeon reimbursement by Medicare decreased as a percentage of direct surgery cost as case complexity increased from poly exchange to tibia-only, femur-only, and both-component revisions. Total hospital cost per average Diagnosis Related Group weight was lowest for single-component revisions and highest for both-component revision.ConclusionThere are significant differences in cost associated with aseptic TKA revisions based on number and type of components revised. These differences may not be accurately reflected in reimbursement, and often represent a burden to those who treat complex revisions.     

Results of Cemented vs Cementless Primary Total Knee Arthroplasty Using the Same Implant Design

Background

Although cemented total knee arthroplasty (TKA) continues to be the gold standard, there are patient populations with higher failure rates with cemented TKAs such as the obese, morbidly obese, and younger active males. Cementless TKA usage continues to increase because of the potential benefits of long-term biologic fixation similar to the rise in cementless total hip arthroplasty. The purpose of this study was to evaluate the clinical and radiographic results of cementless TKA using a novel highly porous cementless tibial baseplate.

Survivorship of Metaphyseal Sleeves in Revision Total Knee Arthroplasty

Background

Metaphyseal fixation has promising early results in providing component stability and fixation in revision total knee arthroplasty (TKA). However, there are limited studies on midterm results of metaphyseal sleeves. We analyzed complications, rerevisions, and survivorship free of revision for aseptic loosening of metaphyseal sleeves in revision TKA.

The Association Between Cement Viscosity and Revision Risk After Primary Total Knee Arthroplasty

BackgroundRecent case series have reported early failure with the use of high-viscosity cement (HVC) in total knee arthroplasty (TKA). We evaluated revision risk after TKA with HVC compared with medium-viscosity cement (MVC) in a large cohort.MethodsWe conducted a cohort study using data from Kaiser Permanente’s Total Joint Replacement Registry. Patients who underwent fully cemented primary TKA for osteoarthritis were identified (2001-2018). Only posterior-stabilized, fixed-mobility designs of the 3 highest-volume implant systems (DePuy PFC, Zimmer NexGen, and Zimmer Persona) were included to mitigate confounding from implant characteristics. Palacos (Zimmer/Heraeus) and Simplex (Stryker) cements comprised the HVC and MVC exposure groups, respectively. Propensity score–weighted Cox proportional hazards regression was used to evaluate risk for any revision during follow-up and risk for revision from aseptic loosening specifically.ResultsThe final cohort comprised 76,052 TKAs, 41.1% using MVC. The crude 14-year cumulative revision probability was 4.55% and 5.12% for TKA with MVC and HVC, respectively. In propensity score–weighted Cox models, MVC compared with HVC had a lower risk of any revision (hazard ratio = 0.82, 95% confidence interval = 0.70-0.95) while no difference was observed for revision from aseptic loosening (hazard ratio = 0.80, 95% confidence interval = 0.56-1.13).ConclusionWhile we observed a lower risk for any revision with the use of Simplex MVC compared with Palacos HVC, we did not observe a difference in revision for aseptic loosening specifically. Given the widespread use of HVC, additional research to investigate other HVC and potential mechanisms for failure outside of loosening is warranted.Level of EvidenceLevel III.     

Isolated Versus Full Component Revision in Total Knee Arthroplasty for Aseptic Loosening

BackgroundRevision of both femoral and tibial components of a total knee arthroplasty (TKA) for aseptic loosening has favorable outcomes. Revision of only one loose component with retention of others has shorter operative time and lower cost; however, implant survivorship and clinical outcomes of these different operations are unclear.MethodsBetween January 2009 and December 2019, a consecutive cohort of revision TKA was reviewed. Univariate and multivariable analyses were used to study correlations among factors and surgical related complications, time to prosthesis failure, and functional outcomes (University of California Los Angeles, Knee Society functional, knee osteoarthritis and outcome score for joint replacement, Veterans RAND 12 (VR-12) physical, and VR-12 mental).ResultsA total of 238 patients underwent revision TKA for aseptic loosening. The mean follow-up time was 61 months (range 25 to 152). Ten of the 105 patients (9.5%) who underwent full revision (both femoral and tibial components) and 18 of the 133 (13.5%) who underwent isolated revision had subsequent prosthesis failure [Hazard ratio (HR) 0.67, P = .343]. The factor analysis of type of revision (full or isolated revision) did not demonstrate a significant difference between groups in terms of complications, implant failures, and times to failure. Metallosis was related to early time to failure [Hazard ratio 10.11, P < .001] and iliotibial band release was associated with more complications (Odds ratio 9.87, P = .027). Preoperative symptoms of instability were associated with the worst improvement in University of California Los Angeles score. Higher American Society of Anesthesiologists status and higher Charlson Comorbidity Index were related with worse VR-12 physical (?30.5, P = .008) and knee osteoarthritis and outcome score for joint replacement (?4.2, P = .050) scores, respectively.ConclusionIsolated and full component revision TKA for aseptic loosening does not differ with respect to prosthesis failures, complications, and clinical results at 5 years. Poor American Society of Anesthesiologists status, increased comorbidities, instability, and a severe bone defect are related to worse functional improvement.Level of evidenceIII, cohort with control.     

High Rate of Re-Revision in Patients Less Than 55 Years of Age Undergoing Aseptic Revision Total Knee Arthroplasty

BackgroundThere are limited data on the outcomes of revision total knee arthroplasty in young patients. We sought to characterize the re-revision-free survival and risk factors for re-revision in patients less than 55 years who underwent aseptic revision TKA.MethodsWe retrospectively reviewed 197 revision TKAs at a mean follow-up of 5 years. Mean age was 49 years; mean body mass index was 31 kg/m². Twenty-seven (14%) patients had at least 1 prior revision TKA. The most common indications for revision included instability (29%), arthrofibrosis (26%), and aseptic loosening (24%). Constraint included the following: 59 posterior-stabilized (30%), 123 varus-valgus constrained (62%), and 15 hinged (8%). Components revised included the following: 93 femur/tibia (47%), 68 polyethylene-only (35%), 19 femur-only (10%), and 17 other (9%). Survivorship free from re-revision was calculated via the Kaplan-Meier method and a multivariate Cox proportional regression was utilized to identify risk factors for re-revision.ResultsSurvivorship free from any re-revision at 5 years was 80%. In the multivariate analysis, patients with a prior revision (hazard ratio [HR] = 2.78, P = .02), an isolated polyethylene exchange (HR = 3.0, P = .004), and a hinged prosthesis (HR = 3.47, P = .05) were significant risk factors for lower revision-free survival. Forty-two patients (21%) underwent re-revision, most commonly for periprosthetic joint infection (7%), instability (6%), and aseptic loosening (5%). Re-revision occurred in 18/68 (26%) patients undergoing an isolated polyethylene exchange.ConclusionPatients less than 55 years undergoing revision TKA have a modest 5-year revision-free survival of 80%. Patients with prior revision TKAs (HR = 2.78), hinge type prostheses (HR = 3.47), and polyethylene-only revisions (HR = 3.0) had higher revision rates.     

Clinical Outcomes in Isolated Tibial Revision With Cruciate Retaining Total Knee Arthroplasty

BackgroundTibial component loosening is one of the most common modes of failure in contemporary total knee arthroplasty (TKA). Limited literature is available on the outcomes of isolated tibial revision with retention of the cruciate retaining (CR) femoral component. The purpose of this study was to determine the results of isolated tibial revisions in CR TKA.MethodsWe identified 135 patients who underwent an isolated tibial revision after a primary CR TKA from our institutional registry between January 2007 and January 2017. The mean time between the primary and revision was 2.9 years (range 0.1-15.4). Revision with a press-fit stem was performed in 79 patients and 56 patients were revised with a fully cemented stem. Patients were evaluated at a minimum of two years using Knee Society Score, Knee Injury and Osteoarthritis Score for Joint Replacement, and radiography. Implant survivorship was determined using Kaplan-Meier survival analysis.ResultsAt a mean follow-up of 5.1 years, there were six (4.4%) repeat revisions: three for periprosthetic infection (2.2%), two for instability (1.5%), and one for a fractured tibial stem (0.7%). The mean Knee Society Score and Knee Injury and Osteoarthritis Score for Joint Replacement increased from 51.6 and 56.1 preoperatively to 90.1 and 89.7 after surgery (P < .001). Survivorship free of repeat revision for any cause was 93.3% at 5 years, and aseptic revision survivorship was 95.8% at 5 years. No implants were radiographically loose.ConclusionIn patients with isolated tibial loosening and a well-fixed and well-positioned CR femoral component, isolated tibial revision provides excellent early to midterm implant survivorship and clinical outcomes with a low risk of instability and recurrent tibial loosening.     

Dissociation of Polyethylene Insert From the Tibial Baseplate Following Revision Total Knee Arthroplasty

Dissociation of a modular tibial insert from the metal baseplate is a rare complication after revision total knee arthroplasty. We herein report an unusual presentation of a polyethylene insert failure that occurred in a posterior-stabilized constrained total knee arthroplasty. The polyethylene insert was posteriorly displaced, which has never been reported in the literature. The assumed mechanism is disengagement of the locking screw after repetitive motion. During knee full extension while standing from a chair, a sudden downward force on the anterior half of the insert caused posterior lift-off of the insert from the tibial baseplate and promoted a sliding force to push the insert posterior when the locking mechanism failed. This unique complication in a fully constrained posterior-stabilized implant should be considered as a cause for implant failure.     

Survivorship and Radiographic Evaluation of Metaphyseal Cones With Short Cemented Stems in Revision Total Knee Arthroplasty

BackgroundThe purpose of this study is to evaluate the survivorship and radiographic outcomes of a single design of metaphyseal cone used in conjunction with short cemented stems.MethodsA retrospective analysis was conducted of revision total knee arthroplasty (rTKA) patients (June 2015 to December 2017) using porous titanium femoral or tibial cones in conjunction with short cemented stems (50-75 mm). Minimum follow-up was 2 years. Survivorship, complications, and a modified Knee Society Radiographic score were analyzed.ResultsForty-nine rTKAs were included in the study (12 femoral cones, 48 tibial cones). Varus-valgus constraint was used in 28 (57%) and a hinged bearing was used in 3 (6%) of these constructs. The majority were index rTKAs of primary components (86%), performed for aseptic loosening (51%) and reimplantation following staged treatment for infection (37%). Median follow-up was 39 months (range 25-58). Using a modified Knee Society Radiographic score, all constructs were classified as stable. Postoperatively, 4 rTKAs were complicated by recurrent infection (8%), periprosthetic fracture 2 (4%), and superficial wound infection 1 (2%). Seven rTKAs (14%) required reoperation. The majority of reoperations (4 rTKAs) were debridement and irrigation with implant retention for infection. Metaphyseal cone constructs with short cemented stems demonstrated 100% survivorship free of revision for aseptic loosening without evidence of radiographic loosening in any case.ConclusionOur results demonstrate excellent outcomes with the use of metaphyseal cones with short cemented stems at mid-term follow-up. This construct avoids the use of long-stem fixation with the associated extraction difficulty, end of stem pain, and potential for malposition at the joint line.Level of EvidenceIV, Case Series.     

Intraoperative Fracture During Aseptic Revision Total Knee Arthroplasty

Bone encountered during revision knee arthroplasty is compromised and predisposed to fracture. This study reports the rate, location, timing, treatment, and outcome of intraoperative fractures occurring during revision knee arthroplasty. Between 1997 and 2011, 2836 aseptic revisions were performed. Ninety-seven fractures were identified in 89 patients (3%). Fifty occurred in femora, 42 in tibiae, and 5 in patellae. Forty-six occurred during exposure, 21 during bony preparation, 17 during trialing, and 13 during final component placement. Treatment included fixation (n = 43), observation (n = 21), component build-up (n = 17), bone grafting (n = 6), and a combination (n = 3). Ninety-four percent of fractures united. Fifteen patients required a re-revision (17%), of which infection was the leading cause (n = 5).     

Modular Tibial Stem Use and Risk of Revision for Aseptic Loosening in Cemented Primary Total Knee Arthroplasty

BackgroundModular tibial stem extensions in total knee arthroplasty (TKA) are designed to reduce the risk of aseptic loosening of the tibial base plate. However, these implants add significant cost and an evaluation of their effectiveness in reducing this risk of loosening has not been studied in a large cohort. We sought to evaluate modular tibial stem utilization in primary TKA.MethodsWe conducted a cohort study using our integrated healthcare system’s Total Joint Replacement Registry. Patients who underwent cemented primary TKA were identified (2009-2019). Propensity scores were used to 1:1 match patients without to those with a stem extension. Cox proportional-hazards regression was used to evaluate the risk for revision due to aseptic loosening.ResultsTen thousand four hundred seventy six TKA with a modular tibial stem were matched to 10,476 TKA without a tibial stem. Stem utilization associated with a lower risk of revision for loosening across all postoperative follow-up (hazard ratio = 0.38, 95% confidence interval = 0.17-0.85).ConclusionIn a matched cohort study, we observed presence of a stem extension was associated with a lower risk of revision for aseptic loosening. Further study to identify specific risk factors for aseptic loosening and confirm the findings presented here are warranted.Level of EvidenceLevel III.     

No Difference in Revision Rate Between Low Viscosity and High Viscosity Cement Used in Primary Total Knee Arthroplasty

BackgroundLoosening remains one of the most common reasons for revision total knee arthroplasty (TKA). Cement viscosity has a potential role in reducing revision rates for loosening. The aim of this study was to assess the outcome for loosening of the 5 most used cemented knee prostheses by constraint type, based on the cement viscosity type used.MethodsThere were 214,708 TKA procedures performed between 1999 and 2020 for a diagnosis of osteoarthritis using the 5 most commonly used minimally stabilized, posterior stabilized, and medial pivot design cemented tibial components. Only procedures with a cemented tibial component were included. Outcomes for two different cement viscosities, 140,060 high viscosity and 74,648 low viscosity cement, were compared for each fixation type within each of the three stability groups.ResultsThere was no difference in a risk of all-cause revision when high viscosity cement was used compared to low viscosity cement for minimally stabilized prostheses (hazards ratio [HR] 1.07 [95% CI 0.99-1.15], P = .09), posterior stabilized prostheses (HR 1.03 [95% CI 0.95-1.11], P = .53), and medial pivot design prostheses (HR 1.06 [95% CI 0.80-1.41], P = .67). No difference was observed between cement viscosity types for any of the prosthesis constraint types when aseptic loosening was assessed.ConclusionsWe found no difference in the risk of revision for any reason, or for loosening, with cement viscosity for the most commonly used minimally stabilized, posterior stabilized, and medial pivot TKA. The role of cement viscosity in the risk of TKA revision remains unclear and further research is required.Level of EvidenceLevel III Retrospective comparative study.     

Morbid Obesity in Revision Total Knee Arthroplasty: A Significant Risk Factor for Re-Operation

Background

The purpose of this study is to compare surgical and clinical outcomes between matched groups of morbidly obese (body mass index [BMI] >40 kg/m²) and non-morbidly obese (BMI <40 kg/m²) patients undergoing first-time revision total knee arthroplasty with a minimum 5-year follow-up.

Long-Term Survival of Semi-Constrained Total Knee Arthroplasty for Revision Surgery

Semi-constrained implants provide stability in the setting of soft-tissue deficiency in revision total knee arthroplasty (TKA). This study evaluated our institution’s long-term survival results with a semi-constrained implant used in the revision TKA setting. 234 semi-constrained revision total knee arthroplasties were performed in 209 patients. The average follow-up was 9 years. Forty repeat revisions were performed. 5-year survival was 91% and 10-year survival was 81%. Male gender significantly increased the risk of revision. At 10 years the average range of motion, pain level, and Knee Society score improved significantly (P < 0.001). Ninety percent of patients reported an improvement in their knee. The semi-constrained implant used in revision knee arthroplasty has acceptable implant survival and functional outcomes in the long-term follow-up period.     

Are the Outcomes of Revision Knee Arthroplasty for Flexion Instability the Same as for Other Major Failure Mechanisms?

Background

Aseptic loosening, infection, and flexion instability have emerged as the leading etiologies for revision after total knee arthroplasty (TKA). Although studies have reported improved outcomes after revision TKA, the relative functional and clinical outcomes of patients revised for flexion instability and other failure etiologies have not been extensively reported. The aim of the study was to compare the functional and patient-reported outcomes of revision TKA for the common failure etiologies.

Short-to-Midterm Outcomes of Revision Total Knee Arthroplasty Patients With a Total Stabilizer Knee System

Background

Revision total knee arthroplasty (TKA) can often be challenging. The use of a new revision system may aid in providing better stability, improved function, fit, and implant longevity. Therefore, we assessed: (1) survivorship, (2) clinical outcomes, (3) postoperative complications, and (4) radiographic outcomes of patients who underwent revision TKA using this system.

Fluoroscopically Assisted Radiographs Improve Sensitivity of Detecting Loose Tibial Implants in Revision Total Knee Arthroplasty

Background

Fluoroscopically assisted radiographs theoretically improve detection of total knee arthroplasty (TKA) implant loosening by providing a better evaluation of the true implant interface, but their utility has not been well studied. We sought to determine whether fluoroscopically guided radiographs improve the sensitivity, specificity, and interobserver reliability of determining TKA implant loosening compared to standard radiographs.

The Natural History of Radiolucencies Following Uncemented Total Knee Arthroplasty at 9 Years

BackgroundAseptic loosening remains a common cause of failure in total knee arthroplasty (TKA). There is an increased interest in using uncemented TKA to reduce this complication. Radiolucencies (RLs) following uncemented TKA can be concerning. We report on the 9-year history of RLs in patients with uncemented TKA.MethodsTwenty-one patients (26 knees) were treated with a cruciate-retaining fully porous coated femur/tibia and cemented patella. At final follow-up, 17 patients (22 knees) were available for review. Average follow-up was 9.6 years, average age was 59.1, and average body mass index was 34.1. X-rays were taken at 6 weeks, 1 year, and at final follow-up. RLs were measured using the Knee Society scoring system and read by two separate surgeons.ResultsAt 6 weeks, we identified RL in all patients on both the tibia and femur. The majority were beneath the tibial tray and femoral chamfer. At 1 year, 4 femurs and 4 tibias showed new RLs (<2 mm) in similar zones. Eighteen femurs and 18 tibias showed fewer or no change in RLs. At final follow-up, no new tibia or femur developed a new RL. In total, 9 of the 22 tibias and 17 of the 22 femurs had remaining RLs, all less than 2 mm and none were progressive or new. Knee Society Score averaged 92.5 (6 weeks), 95.1 (1 year), and 97.3 (final).ConclusionRLs are common following uncemented TKA. Many resolve by 1 year. There does not appear to be any association between the presence of RLs and long-term follow-up function in this group of patients.     

Results of Cemented Posterior-Stabilized Total Knee Arthroplasty in Obese Patients With an Average 10-Year Follow-Up

BackgroundObese and morbidly obese patients undergoing primary total knee arthroplasty (TKA) place significant stress at the bone-cement-implant interface over the life of the patient. The purpose of this study is to evaluate results of cemented, posterior-stabilized TKA in obese and morbidly obese patients at an average follow-up of 10 years.MethodsRetrospective study of 181 patients who had a cemented, posterior-stabilized TKA between 2000 and 2013 with body mass index >35 at the time of surgery was conducted. Clinical data and radiographs were evaluated along with survivorship, complications, and revisions. Minimum follow-up was 5 years with an average follow-up of 10 years.ResultsThere were 135 women and 46 men in the study, with mean age of 60.2 years (range 43-80), mean body mass index of 42.0 (range 35.1-66.1), and an average follow-up of 10 years (range 5-18). There were a total of 39 failures (22%) that underwent revision TKA surgery with mean time to revision of 8 years. Failures included 25 (14%) cases of aseptic loosening; 9 (5%) polyethylene wear; 2 (1%) prosthetic joint infection; and 3 additional revisions for instability, pain, and stiffness. There were a total of 11 cases of isolated tibial component loosening and 13 for both tibial and femoral loosening. Survivorship at 15 years with aseptic loosening as the endpoint was 86.7%, and for all causes 79.6% at 15 years.ConclusionAseptic loosening is the leading cause of failure following TKA in obese and morbidly obese patients with decreasing survivorship from 96.1% to 91.2% and 86.7% at 5, 10, and 15 years, respectively.     

Long-Term Outcome Following Revision Total Knee Arthroplasty is Associated With Indication for Revision

BackgroundThere is limited information about long-term clinical outcomes following revision total knee arthroplasty (TKA) in relation to the indication for revision. Previously, a clear relation between indication for revision and clinical outcome was shown after 2 years. Present study evaluated (1) whether the reported association at 2 year remains present at 7.5 years, and (2) how clinical outcome at 7.5 years developed compared to baseline and 2-year follow-up, and (3) whether patients had additional adverse events.MethodsA cohort of 129 patients with a total system revision TKA was selected. Range of motion, Visual Analog Scale for pain and satisfaction, and clinical and functional Knee Society Score were obtained preoperatively, at 3 months, 1, 2, and 7.5 years. Reasons for revision were septic loosening, aseptic loosening, malposition, instability, and severe stiffness.ResultsPatients revised for severe stiffness had significantly worse outcomes. No difference was found between the other indications. The clinical outcome after revision TKA at 7.5 years remained stable for septic and aseptic loosening, malposition, and instability but deteriorated slightly for the severe stiffness group. Visual Analog Scale satisfaction remained constant for all indications. There were 11 additional complications between 2- and 7.5-year follow-up, 9 of which necessitated reoperation.ConclusionAll indications except severe stiffness had a similar clinical outcome which was maintained up to 7.5-year follow-up. The severe stiffness group had worse outcomes and deteriorated slightly at longer follow-up. Outcome at 3 months seems predictive for long-term outcome. Additional complications did not differ significantly for the different reasons for revision.Level of EvidenceLevel III, prognostic study.